Electric-heater system.



W. L. WATERS.

ELECTRIC HEATER SYSTEM.

APPLICATION FILED NOV. 13. 1913.

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ELECTRIC HEATER SYSTEM.

APPLICATION FILED NOV-13,1913.

l ,1 83,925 Patented May 23, 1916.

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ELECTRIC HEATER SYSTEM.

APPLICATION FILED NOV 13. 1913.

1,1 83,925. Patented May 23, 1916.

3 SHEETSSHEET 3.

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WILLIAM L. WATERS, OF IVIILWAIIKEE, WISCONSIN.

- ELECTRIC-HEATER sYs'rnM.

Patented May 23, 1.916.

1,183,925 Specification of Letters Patent.

6 Application filed November 13, 1913. Serial No. 800,707. 1 i

To all whom ztma'y concern: rent ls broken by the ma n switch. Flg.

Be it known that 1, WILLIAM L. WATERS,

a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Electric,

Heater Systems, of which the following isa full, clear, concise, and exact description, reference being had to, the accompanying drawings, forminga part of thisspecification.

My invention relates to the art of electric heating, and is concerned with a system adapted to be employed. where it is desired to maintain substantially constant the temperature of a body, such as a tank containing molten metal, such as is used for linotype work; or oil, such as is used for tempering steel; or, in fact, solid bodies such as printing dies. Y a The primary object of my inventionis to maintain the substantially constant temperatureautomatically and to secure this result by means of an efficient, economically.

operating, and simple arrangement, wherein the necessary circuit-changing devices are not subjected to heavy heating currents, but, on the contrary, are required to carry only light relay currents, and wherein sparking at contact points is avoided.

To the end of eflicient and economical operation, it is my preferable plan to provide two or more heating elements of different characteristics, so that certain burdens, such as the steady one of continuously keeping the temperature up to at least a certain point,'may be carried by a heating element having a low in-put, while the special services, such as maintaining a constant temperature and raising the temperature rapidly, may be carried out by a heating element of high in-put.

'In the accompanying drawings 1 have illustrated variousarrangements coming within the scope of my invention.

In the accompanying drawings, Figure 1 is a diagrammatic illustration of one embodiment of invention. Fig. 2 shows a modification having one heating element permanently connected to the mains. Fig.

3 illustrates the system of Fig. l, employing a difierent type of thermostat. Fig. 4 illustrates a modification in which therelay cur expansion, said bulb being connected by" means of a tube 8 with the expansible memher 9 of a- Bourdon gage. The end of this expansible member is connected by means of a link 10 with a pointer 11 pivoted at 12. This pointer is adapted to make engagement with either one of the two contacts 13 and 14:. The arrangement is merely diagram matically illustrated and it will be seen that T- have illustrated a winding 15 and a winding 16 in association with the vessel 6,

it being understood that these windings are so related to the vessel that when currents pass therethrough they heat the vessel and the contents thereof. 1 shall refer to the coil 15 as the constant temperature coil and to the coil 16 as the high temperature coil, and it is an important feature of my invention that the coil 15 is of comparatively high resistance and low wattage while the coil 16 is of comparatively low resistance and-high wattage- These coils are diagrammatically illustrated as being disposed 1n difierent parts of said heating vessel 6 but may be placed. in any preferred locatlon. The coil 16 is adapted to be connected across the line limbs a, b by connecting together two contacts 17 and 18. This is done by means of a contact maker 19 carried by the solenoid core 20 mounted so as to be subject to the influence of a solenoid coil 21 and another solenoid coil 22. It will be seen that when the contact maker 19 simultaneously engages the contacts 17 and 18 the co l 16 is connected directly across the hue limbs a and b.

The solenoid core 20 carries another contact maker 23 which is adapted to close the circuit between the contacts 24. and 25. This action closes the circuit of the coil 15 across gagement vwith the contacts 17 and 18 so as to close the circuit through the high temperature winding 16. This operation brings the vessel and its contents up to the desired temperature and it does this quickly so that no time is lost in getting the operation under way.- The calibration of the Bourdon gage is such that when a definite figure, say 500 degrees centigrade, is reached, the contact pointer 11 will have reached. the contact 13 and this operation closes the circuit'through the solenoid winding 22. This brings contact maker 23 into engagement with the contacts 24 and 25, so

that the winding 15 is thrown into the circuit and this winding is practically sufficient to maintain a constant temperature by supplying the radiation losses. However, if the winding 15 should not be suflicient to completely supply the radiation losses or if the addition of cold objects should lower the temperature of the bath of melted material the decrease in temperature causes the pointer 11 to travel back toward the contact 14, .and when a predetermined minimum temperature, say 450 degrees centigrade, is reached, the pointer'll will make engagement with the contact 14 and will throw the solenoid 21 into circuit so as to substitute the high temperature winding for the constant temperature winding to bring up the'temperature to the proper point. Here, again, when the maximum temperature is reached, the solenoid 22 operates to make the substitution of the windings. In this way the temperature is 'maintained between 450 degrees and 500 degreescentigrade, and in'securing this result the main burden is carried by the winding of low in-put while the winding of high in-put is arranged to perform other services in'the way of initially bringlng up the temperature and being periodically brought into circuit to raise the temperature to the required point.

It will now be seen that when the switch 19 is closed the coil 21 and the contact between the pointer 11 and the member 14 are short-circuited so that as the temperature rises and the Bourdon gage causes the pointer to move from the contact 14 there will be no arc resulting with the consequent destructive spark. that when the engagement between the It will also be noted this switch is opened. the circuit controlled by these contacts is also opened so that no sparking can result as the temperature drops again and the pointer leaves the member 13. Thus in both cases when the gage pointer leaves the contacts the circuit conditions are such that no sparking can result at these contacts and any destructive arcs are entirely eliminated. The heavy heating currents are controlled alone by the relay contacts, which are separated quickly and which may be constructed to carry the proper amount of current.

In Fig. 2 I have provided the various parts with reference characters which are analogous to those of Fig. 1, so far as they apply, and it will be seen that the only dif ference between the arrangement of Fig. 2 and that of Fig. 1 lies in the fact that the constant temperature coil. 15 is placed permanently across the line limbs a and b so that the constant heat is given by the winding 15 alone and the special heat is given by the windings 15 and 16 acting conjointly.

Fig. 3 will be seen to be like Fig. 1, ex-

cept that the Bourdon gage 9 is replaced by to the maximum contact 13 and as it contractsthe reverse movement takes place.

In Fig. 4 it will be seen that the same elements are present as in Fig. 3 in which a separate switch is introduced to open the circuit through the pointer 11 and contact 13 when the heater 16 is thrown into circuit, so that there will be no spark when the pointer leaves the stop. This additional switch is illustrated at 27, 28 and 29, and it will be seen that when the coil 22 is energized at the time the pointer 11 reaches the maximum stop 13 the circuit of the coil and the contacts controlling it is opened, so that when the temperature falls again and the pointer 11 leaves the contact 13 there will be no ossibility of a spark. n Fig. 5 I have illustrated a form SlIIlllar to Fig. 4, except that the constant temperature winding is always in circuit so that one of the switches is dispensed with.

In every instance the heating is secured by the cooperation of two coils, with the constant temperature coil being either always in the circuit or in the circuit most of the time so as to maintain a substantially constant temperature nearly equal to the desired temperature and particularly adapted to counteract the radiation losses. The coil I of high in-put, which throws a large amount of heat into the object quickly,

comes into service either in substitution for the other coil or in addition thereto and is put out of service immediately after it has performed its function-that of either primarily bringing up the temperature when the apparatus is first set into operation or of supplying a deficiency to bring the temperature between the prescribed limits. .Since thisji coil of high in-put is automatically brought into service at the times when more heat is required, as has been described, it will be clear that the temperature will automatically be maintained between the two prescribed limits.

In addition to claiming the more comprehenslve features oi my invention, I also cla1m the more specific features, which are .none the less important, whereby the controlllng contacts are effectively protected from the heavy cui-rents which will necessarily be requ1red tp effect the proper heat- 1ng. TlllS I do without serious complicating the circuit which I propose and without the employment of; expensive switching or additional relay apparatus, the relay currents being controlled by the same electromagnetic mechanism which is required to bring the proper cdils into active service. i I have described; in detail a specific embodiment of my invention, but in order to secure certain advantages of my invention it is unnecessary td follow exactly the specific construction set forth in the I description of the illustrations. I K

' While it is preferable to use a heating element of high input and another heating element of low input it will be possible, and novel and advantageous in some instances, to use heating elements of equal input or heating elements of a reverse relation. It

is essential, however, that two heaters are employed, one of which can be substituted for the other or can be added to the other in its heating effect, and I have drawn the v appended claims with this in mind.

I claim as new and desire to secure by Letters Patent:

1. In a heating system, a heating unit of high in-put, a heating unit of low in-put,

and thermostatically controlled means for automatically substituting either of said coils for the other l 2. In a heating'system, in combination, a heating coil of low electrical in-put, an independent heating coil of high electrical "in-put applied to ia body to be heated, a

thermostat responsive to the temperature of the heated body, arid electromagnetic means mostatsubject to the temperature of said body, a switching arrangement arranged to close one heater circuit when a prescribed maximum l; temperature is reached and to qlose another heater circuit when a prescribed minimum temperature is reached, a relay winding in. each of said circuits, and relay contacts cb'ntrolled by said windings and controlling'the circuits of said heater units.

4. In a heating system, a heating unit of low in-put, a heating unit of high in-put, both applied to a body to be heated,'a thermostat subject to the temperature of said body, a switching arrangement arranged to close the circuit of said first unit when a prescribed 'maximum temperature is reached and to close the circuit of said second unit when a prescribed minimum temperature is reached, ali relay winding in each of said circuits, aiid relay contacts controlled by said windings and controlling the circuits of said heating units, the circuits of said relays being made by said thermostatically controlled .means and being broken by their own contafct mechanism.

5. In an electric heating system, a heating element, an electromagnetic device controlling the circuit of said heating element, and thermostatically controlled contact mechanism to govern the circuit of said electromagnetic device, said electromagnetic device being [arranged to short-circuit the thermostatically controlled contacts when enerze 6. In a heating system, in combination, a body to be heated, a heating unit of low resistanc and high wattage and a heating unit of high'resistance and low wattage applied to said body, contact mechanism controlling the circuits of said units, electromagentic means for controlling said contact mechanism, thermostatically controlled means for governing the circuit of said electromagnetlc means, said thermostatically controlled means being adapted to make the circuit of one electromagnetic means when a prescribed minimum temperature has been reached so as to bring the unit of low resistance and high wattage into circuit and to open the circuit of the other unit, said thermostatically controlled means being also adapted to close the circuit throu h the electromagnetic means for bringing the unit of high resistance and low wattage into circuit and cutting the other unit out of circuit when the temperature has reached. the prescribed maximum.

7. In a heating system, heating units, relays controlling said units, thermostatically controlled contacts for controlling said relays, and means for short-circuiting said thermostatically controlled contacts when they have closed their circuit.

8. In a heating system, heating units, relays controlling said units, thermostatically controlled contacts for controlling said relays, and means for interrupting the current flowing through said contacts by opening the circuit at another point.

9. In a heating system, a heating unit, an auxiliary heating unit, and means for auto-\ matically substituting either of said units for the other.

10. In a heating system, a heating unit, an auxiliary heating unit, both applied to a body to be heated, a thermostat subject to the temperature" of said body, a switching arrangelirentarranged to close a circuit for said heating unit when. a prescribed maximum temperature is reached and to close a circuit for said auxiliary heating unit when a prescribed minimum temperature is reached, a relay Winding in each of said circuits, and relay contacts controlled by said windings and controlling the circuits of said heating units.

11. In a heating system, a heated element, a plurality of heaters of different heating capacities for heating said element, automatic heat controlled switching means, said means substituting a heater of hlgher wattage for a heater of lower wattage when the temperature of said element, as a whole, falls to a predetermined value, and. substituting a heat of lower wattage when the temperature rises to a predetermined value.

'12. In a heating system, a body to be heated, a heating coil of loWin-put, an independentheating coil of high in-put, said coils being disposed in different parts respectively of said body to be heated, a thermostat, responsive to the temperature of said body, electromagnetic means controlled by said thermostat for openin and, closing the circuits of said units, and 0% 13. In an electric heating system, a heating element, an 'electro-magnetic device controlling the circuit of said heating element and thermostatically controlled mechanism togovern the operating circuit of said electromagnetic device, operation of said electro-magnetic device, changing the flow of current through said thermostatic contact mechanism to prevent sparking upon the separation of the thermostatic contacts in response to the temperature changes.

14. In a heating system a plurality of heating units, thermostatic contact means, relay means controlled by said thermostatic contact means, said relay means having a pair of operating coils and contact means for changing the connections of said heating unit relatively to each other, circuits connecting said thermostatic contact means, said heating units and said relay means, the coils of said relay means being supplied with current only during the period of movement of the contact mechanism controlled thereby.

In witness whereof, I hereunto subscribe my name this 8th day of November, A. D. 1913. I

WILLIAM L. WATERS.

contact said thermostat. 

